1. Field of the Invention
This invention relates to a fire isolation device which is biased to close upon reaching a given temperature and more particularly to such a device including a fusible member holding a self-closing valve open prior to reaching the given temperature.
2. Description of the Prior Art
U.S. Pat. No. 3,245,423 Hansen, et al.; U.S. Pat. No. 195,367 Hiller; U.S. Pat. No. 1,930,624 Ryan and U.S. Pat. No. 2,048,387 Johnsen all relate to valve couplings with fusible safety cutoff means. These devices are generally for lower temperature applications than that of the subject invention and all employ the use of a fusible material around the outside diameter of a member such that when the material melts the member moves permitting a biased poppet to close a valve. They are used for applications such as boiler protection.
Another group of patents, U.S. Pat. No. 2,305,841 Carlson, U.S. Pat. No. 2,434,167 Knoblauch and U.S. Pat. No. 2,850,297 Clark disclose quick disconnect couplers which are designed to prevent loss of fluid flow when the coupling is disconnected. These devices employ no fusible materials.
U.S. Pat. No. 3,659,624 Kelly, et al., U.S. Pat. No. 3,842,853 Kelly, et al. and U.S. Pat. No. 3,896,835 Wicke all disclose gate valves. Kelly, et al. 624 employs a locking ring 50 of fusible material which when upon melting allows expansion of the locking fingers 52 permitting the gate valve to close. Kelly, et al. 853 employs a fusible disk 173 which upon melting is extruded through the port 171 permitting the piston member to close the gate valve. Wicke employs a similar structure. None of these last three references employ a fusible nose member in the flow path through the gate valve.
U.S. Pat. No. 3,618,627 Wagner discloses a temperature responsive pressure relief employing a fusible material behind a spring biased poppet which opens upon over temperature.
U.S. Pat. No. 4,225,760 Griffith, et al. discloses a pressure responsive valve which closes when plug 54 melts by means of fluid pressure such that there is some loss of fluid prior to closure.
In accordance with an aspect of the present invention, it is an object to provide a new and improved fire isolation device capable of operating at high temperatures such as 2000.degree. F for up to 15 minutes which employs a fusible member through which the fluid normally flows which biases a valve poppet open.
Another object is to provide such a device which is bidirectional, having a valve member held open by a fusible nose member in both ends thereof.